Although plastic molded products made of polycarbonate resin or acrylic resin and so on are used in a wide range of applications due to their superior transparency and ease of processing, if the surface temperature thereof falls below the dew point temperature, moisture in the atmosphere forms fine water droplets that condense resulting in fogging, thereby resulting in the problem of a loss of transparency. Various studies were conducted in the past for imparting anti-fogging properties to the surface of molded products while also generating charge prevention by making the surface of these molded products hydrophilic.
Methods for forming an anti-fogging coating on the surface of a base material are known in the prior art, and various photocurable compositions for forming an anti-fogging coating consisting of forming a curable coating by irradiation with ultraviolet light and so on have been proposed in consideration of workability and other factors. For example, Japanese Patent Application Laid-open No. Hei 6 (1994)-136165 and Japanese Patent Application Laid-open No. 2001-19874 disclose an anti-fogging agent containing polyethylene glycol diacrylate, a surfactant and a photopolymerization initiator. In addition, Japanese Patent Application Laid-open No. Hei 11 (1999)-140109 discloses an anti-fogging composition containing a (meth)acrylate having at least two hydroxyl groups and at least two (meth)acryloyl groups in a molecule thereof, and a reactive surfactant. Moreover, Japanese Patent Application Laid-open No. 2003-12743 discloses an anti-fogging composition containing a (meth)acrylamide-based compound, a urethane polymer, polyalkylene glycol acrylate and a photopolymerization initiator.
On the other hand, compositions containing components photocured by radical polymerization in the manner of (meth)acryloyl group-containing compounds are susceptible to curing inhibition by oxygen present in the atmosphere in which the coating surface is irradiated in the case of forming a coating as a result of being cured by irradiation with ultraviolet or other light. In order to counteract this, methods have been proposed involving the use of a large amount of photopolymerization initiator, irradiating the coating with a high-output lamp, or as described in Japanese Unexamined International Patent Publication No. 2003-515445, irradiating the coating with light in the presence of an inert gas.
However, the compositions disclosed in the above-mentioned Patent Application Laid-open No. Hei 6 (1994)-136165, Japanese Patent Application Laid-open No. 2001-19874 and Japanese Patent Application Laid-open No. Hei 11 (1999)-140109 all have inferior adhesion to the surface of the base material. In addition, although the coating formed from the composition described in Japanese Patent Application Laid-open No. 2003-12743 offers a certain degree of sustained anti-fogging performance, when exposed to high-temperature conditions during use or high-humidity conditions due to rainfall for an extended period of time as in the manner of automobile headlights, there is the problem of decreases in anti-fogging performance and adhesion.
In addition, when coatings composed of the compositions described in the patent publications listed above are irradiated with light in an inert gas atmosphere, although resistance of the coating surface to friction improves to a certain extent, the problem of decreases in anti-fogging performance and adhesion remains unsolved.